Hey mook, it is my understanding the Interstate COMMERCE Commission was created in response to shippers complaints about high rates & monopoly practices of railroads of the day. Safety concerns were also an early issue. Later on the commission would become heavily involved in regulating trucking rates & geographic service areas , & river barges as well, for the same reasons.
Perhaps this is splitting hairs, but your comment that the I.C.C. " was set up to prevent unregulated competition between freight haulers( initially pretty much railroads )", did have real benefit to shippers in the form of uniform rates & guaranteed service to every siding & town. The only real benefit to railroads was to the weak ones that otherwise could not compete, as they were now also guaranteed minimum rates for services rendered.
In the example of CORP & the Siskiyou Line, the directed service proceedings are not to CORP's advantage; in fact it was shippers' complaints about new surcharges for service over the line that began the process.
In the many " Train - Off " petitions & abandonment filings that I have read about, the term " Public need & necessity " is often quoted. Aren't shippers considered part of the public ???